Typical end closures for beer and beverage containers have an opening panel and an attached leverage tab for pushing the opening panel into the container to open the end. The container is typically a drawn and ironed metal can, usually constructed from a thin plate of aluminum. End closures for such containers are also typically constructed from a cutedge of thin plate of aluminum or steel, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion.
These types of container ends have been used for many years, with almost all such ends in use today being the “ecology” or “stay-on-tab” (“SOT”) ends in which the tab remains attached to the end after a tear panel, including large-opening ends (“LOE”), is opened. The tear panel being a portion of the can end defined by a frangible score length and a non-frangible hinge segment. The tear panel may be opened, that is the score may be severed, and the tear panel displaced at an angular orientation relative to the remaining portion of the can end, thus creating a pour opening through which the beverage may be poured from the container. The tear panel remains hingeably connected to the remaining portion of the can end by the non-frangible hinge segment, leaving an opening through which the user draws the contents of the container. In an LOE, the pour opening is about 0.5 square inches in area.
Opening of the tear panel is operated by the tab which is attached to the can end by a rivet through a rivet island on the tab. The tab is typically attached to the can end such that a nose of the tab extends over a proximal portion of the tear panel in a stowage position. A lift end of the tab is located opposite the tab nose and provides access for a user to lift the lift end, such as with the user's finger, to force the nose against the proximal portion of the tear panel. With most can ends, the stowage position and opening position are in the same location; however, some can ends known in the art require rotation of the tab from a stowage position to the opening position prior to an opening sequence, i.e. the fracturing of the frangible score.
When the tab nose is forced against the tear panel, the score initially ruptures at a vent region of the score. This initial rupture of the score is primarily caused by the lifting force on the tab resulting in lifting of a central region of the can end, including the rivet and immediately adjacent the rivet. As the tab is lifted further, the score rupture propagates along the length of the score, eventually stopping at the hinge segment.
Venting is an initial release of pressure from within a pressurized container upon initial fracture of the score about the tear panel, typically upon the initial lifting of the lift end of the tab by a user.
In general, beverage can end design requires a careful balancing of structural elements to achieve a beverage can end of a desired strength while maintaining proper function of the SOT opening assembly. Changes to one structural element to improve one physical characteristic of the beverage can end will routinely adversely affect a different physical characteristic.
For example, strengthening the can end through localized coining, or the compression of the metal to produce a localized region of reduced thickness, will create a volume of excess metal that typically must be used to form some structure, else it could have an adverse effect on performance of the can end. Oil can-effect or warping of the center panel often results from coining or other processes that create a localized excess volume of metal.
Additionally, if a designer selects a score line depth which is too deep, the resulting can ends are subject to being ruptured during the production and during packaging and shipping operations. On the other hand, if the score depth is too shallow, excessive force may be required to rupture the score. In such a situation, even if the user is physically able to apply sufficient force to rupture the score line, the tab and the tear panel itself may deform in a manner to prevent complete rupture of the full length of the score.
It is desirable to have a tear panel that is stiff and resists deformation during the opening procedure. The tendency of a tear panel to deform excessively during score rupture is to a large extent, a function of the relative stiffness of the tear panel. The stiffness of a tear panel may, in turn, be influenced by the metal gauge, i.e., the thickness of the tear panel, and also the amount of “slack”, or localized excess, metal in the tear panel. Tear panel slack may be produced by various sources including rivet formation and also the very scoring needed to create a tear panel. The relative size of a tear panel also affects the rupture performance of a tear panel since a panel of larger area tends to bend more and thus diffuse the rupture force applied by the tab more than a smaller tear panel of the same metal gauge.
One common technique used for increasing the relative stiffness of a tear panel is to create a deboss panel which circumscribes the tear panel and rivet and in which the tear panel and the rivet are recessed.
Another technique is to form a raised or “embossed” metal bead in the middle of the tear panel to take up metal slack. The tear panel may also have a deboss bead. The deboss bead may have a surface portion which ramps upwardly and radially inwardly, relative to an axis passing through the staked portion of the tab and oriented generally normal to the generally flat, radially extending surface. In either case, the bead structure is formed in a shape which generally follows the geometric shape of the score of the tear panel, thereby evenly drawing slack metal from the tear panel. The bead structure may also be used to provide better leverage by opening force on the tear panel by the tab.
Thus, the structure of the beads on the tear panel, including placement, depth/height, shape, surface area, and volume are of the utmost importance in the functionality and operation of the can end overall and, in particular, performance during the severing of the frangible score during opening. For this reason, there have been no known efforts to use the tear panel as a means for conveying information to a user through beading or other structures. Again, any structural change to the tear panel would have an effect on can end performance. Any non-uniform, irregular shaped bead could place unwanted forces on the frangible score. Additionally, any coining or additional scoring could create slack metal in the tear panel that would adversely affect can end openability.
Prior art can ends have been used to convey information to users. Recycling instructions, manufacturing codes, and the like have been incised or scored into a public surface of a center panel of the can end and outside a perimeter of the tear panel. The alpha-numeric symbols used to convey information are typically very shallow. Typically, emboss and deboss beads are not employed.
More recently, and with some success, the tab has been used to convey information to users. This information may be in the form of promotional materials, logos, or the like. Methods such as printing, incising, laser ablation, stamping, beading, etc. have been proposed to provide information on the tabs. The tab is used for this purpose because changes to the tab are less likely to adversely affect beverage can end performance. However, the available surface area on the tab is very limited for these purposes, even when enclosing the finger hole to create a billboard-like surface on the tab.
The inventors have identified a commercial need to expand the use of information-conveying symbols on can ends. It would be desirable to utilize a larger surface area of the can end in a more prominent location on the center panel, wherein a user is naturally encouraged to view the information carrying symbols in the manner intended by the designers. The tear panel is the most likely location for such symbol due to its location on the center panel and because the tear panel naturally faces the user when the user lifts the tab to begin an opening sequence of the can end. However, the structural importance of the tear panel during manufacturing and during the severing of the frangible score have generally eliminated the tear panel from consideration for communicating information in the form of structural symbols to a user.
Thus, the problem addressed by the inventors can be stated: In a beverage can end or lid comprising a stay-on-tab ecology opening assembly, where is a desirable location for information-communicating symbols on a public side of a center panel; and what are the structural requirements of a displaceable tear panel having information-communicating structural elements thereon when the stay-on-tab opening assembly and the beverage can end must maintain the physical and functional properties required of a properly opening beverage can.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior can ends of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.